Police were trying to flush a survivalist suspected of killing a state police trooper out of the dense, swampy northeastern Pennsylvania woodland on Friday, the seventh day of a manhunt.

Police say they are eliminating possible hiding places for the suspect, 31-year-old Eric Frein, including hunting cabins, campsites and other occasional residences in the Pocono Mountains. An intense late-night search Thursday concentrated on the area around Frein's parents' home, with roads blocked and residents kept from their homes temporarily.

"We're systemically taking away any opportunities for him for cover and concealment, for any comfort," Lt. Col. George Bivens told reporters Thursday afternoon, hours after the funeral for Cpl. Bryon Dickson.

Frein is charged with killing Dickson, 38, and wounding Trooper Alex Douglass in a late-night ambush Sept. 12 outside the Blooming Grove barracks. As many as 200 law enforcement officers at a time have been casting a wide net around the crime scene, exploring rugged terrain so impenetrable in spots that police choppers can't see through the forest canopy.

Schools in the area will be closed again Friday as authorities look for Frein, who was added Thursday to the FBI's 10 most wanted list. A total of $175,000 in reward money is being offered for information leading to his arrest.

"We have now made the world where he could hide a very, very small place," said Edward Hanko, special agent in charge of the FBI's Philadelphia office.